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National Centers for Environmental Information (NCEI)

California Coast from Point Conception to Point Sur
USGS Open File Report 88-224

Data Announcement 89-MGG-01

     During the fall of 1979, the U.S. Geological Survey (USGS) collected approximately 680 km of 24-channel seismic-reflection data across the continental margin in the eastern Pacific Ocean off of the California Coast between latitude 34 degrees and 37 degrees north. The USGS has provided these data to the National Geophysical Data Center (NGDC) (now the National Centers for Environmental Information (NCEI)) for public dissemination.

     The data were collected on the USGS research vessel S.P. LEE during cruise L5-79-NC using a sound source of five airguns totaling 1,326 cubic inches at a manifold pressure of approximately 1900 psi. The recording system consisted of a 24- group streamer, 2400 meters long, and a GUS (Global Universal Science) model 4200 digital recording unit. Records were sampled in the field at a 2-msec rate and later processed at a 4-msec rate. The seismic reflection records vary in length from 8 to 12 seconds depending on water depth and geologic structure. The data have been edited, NMO-corrected, CDP-sorted, stacked, deconvolved, filtered and finally graphically displayed by an electrostatic plotter. Processing was carried out at the USGS Marine Geology Seismic Processing Center in Menlo Park, California. Navigational control for the survey was by satellite fixes augmented by Loran C (Rho-Rho) and Doppler-sonar bottom- track navigation.

     The seismic data are available as plastic or paper sections, horizontal scale 20 traces/in. vertical scale 1.25 in/sec, as digital magnetic stack tapes, or as digital magnetic demultiplexed tapes.

DATA AVAILABLE (please refer to 9-digit product numbers when ordering).

9 seismic profiles (24 channel)
      (plastic sepia) Product #976F20170
      (paper sepia) Product #976F19170
      (blackline) Product #976F18170

1 trackline chart (scale: 1:500,000). Product #976A18170

1 magnetic tape containing shotpoint navigation, Product
#976H07170. This is also available on CD-ROM, Product
#129F27001. 9 digital magnetic stack tapes. Product #976L07170
9 digital magnetic demultiplexed tapes. Product #976L07171